Exposure to an electrostatic discharge (ESD) may cause damage to the internal circuits of electronic components used in communication devices. ESD is caused when an electronic device contacts an object capable of transferring electric charges, static electricity is discharged to influence a circuit. For example, ESD may occur when a human body contacts an antenna or an external connector part of a communication device.
In order to protect internal circuits from ESD, an electronic circuit is equipped with an electrostatic protection device. The electrostatic protection device may be realized with a semiconductor device such as a transistor. For example, if the electrostatic protection device is realized using a metal oxide semiconductor field effect transistor (MOSFET), a gate insulation layer is formed on and/or over a channel region between a source region and a drain region, and a gate electrode is formed on and/or over the gate insulation layer.
Since the gate insulation layer has a very thin thickness of several tens of Å to several hundreds of Å, it has a tendency to be easily broken even when a current of more than several tens of V flows. Therefore, a transistor may lose its function as a electrostatic protection device. Particularly, although static electricity has high voltage and low current characteristics, the gate insulation layer of a transistor has a lattice structure that can be easily broken at a voltage level of static electricity. Additionally, different electrostatic protection devices need to be provided based on current characteristics of various circuit devices, and also the durability of the electrostatic protection device is deteriorated due to frequent exposures to an overcurrent. At the product development stage, if the reliability of an electrostatic protection device is tested, it is difficult to predict its durability. Additionally, there is limitation in enhancing the degree of integration of an electrostatic protection device because it is connected to a circuit device as an external device through an additional mounting process. Moreover, the electrostatic protection device differentially operates in accordance with an overcorrect occurring at the inside and outside thereof.